References of "Frankignoulle, Michel"
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See detailAn artificial neural network analysis of factors controlling ecosystem metabolism in the coastal ocean
Rochelle Newall, Emma J.; Winter, Christian; Barrón, Cristina et al

in Ecological Applications (2007), 17(5), 185196

Knowing the metabolic balance of an ecosystem is of utmost importance in determining whether the system is a net source or net sink of carbon dioxide to the atmosphere. However, obtaining these estimates ... [more ▼]

Knowing the metabolic balance of an ecosystem is of utmost importance in determining whether the system is a net source or net sink of carbon dioxide to the atmosphere. However, obtaining these estimates often demands significant amounts of time and manpower. Here we present a simplified way to obtain an estimation of ecosystem metabolism. We used artificial neural networks (ANNs) to develop a mathematical model of the gross primary production to community respiration ratio (GPP:CR) based on input variables derived from three widely contrasting European coastal ecosystems (Scheldt Estuary, Randers Fjord, and Bay of Palma). Although very large gradients of nutrient concentration, light penetration, and organic-matter concentration exist across the sites, the factors that best predict the GPP:CR ratio are sampling depth, dissolved organic carbon (DOC) concentration, and temperature. We propose that, at least in coastal ecosystems, metabolic balance can be predicted relatively easily from these three predictive factors. An important conclusion of this work is that ANNs can provide a robust tool for the determination of ecosystem metabolism in coastal ecosystems. [less ▲]

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See detailOrganic carbon metabolism and carbonate dynamics in a Mediterranean seagrass (Posidonia oceanica) meadow
Barrón, Cristina; Duarte, Carlos M.; Frankignoulle, Michel et al

in Estuaries and Coasts (2006), 29(3), 417-426

in a Posidonia oceanica meadow and unvegetated sediments of Magalluf Bay (Mallorca Island, Spain) to determine gross primary production (GPP), community respiration (R), and net community production (NCP ... [more ▼]

in a Posidonia oceanica meadow and unvegetated sediments of Magalluf Bay (Mallorca Island, Spain) to determine gross primary production (GPP), community respiration (R), and net community production (NCP). From June 2001 to October 2002, we also measured fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TAlk). The yearly integrated metabolic rates based on DO changes show that the P. oceanica communities are net autotrophic while the metabolic rates in the unvegetated benthic communities are nearly balanced. Higher calcium carbonate (CaCO3) cycling, both in terms of production and dissolution, was observed in P. oceanica communities than in unvegetated benthic communities. In the P. oceanica meadow, the annual release of CO2 from net CaCO3 production corresponds to almost half of the CO2 uptake by NCP based on DIC incubations. In unvegetated benthic communities, the annual uptake of CO2 from net CaCO3 dissolution almost fully compensates the CO2 release by NCP based on DIC incubations. CaCO3 dynamics is potentially a major factor in CO2 benthic fluxes in seagrass and carbonate-rich temperate coastal ecosystems. [less ▲]

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See detailResponse of primary production and calcification to changes of pCO(2) during experimental blooms of the coccolithophorid Emiliania huxleyi
Delille, Bruno ULg; Harlay, Jérôme ULg; Zondervan, Ingrid et al

in Global Biogeochemical Cycles (2005), 19(2),

[1] Primary production and calcification in response to different partial pressures of CO2 (PCO2) ("glacial,'' "present,'' and "year 2100'' atmospheric CO2 concentrations) were investigated during a ... [more ▼]

[1] Primary production and calcification in response to different partial pressures of CO2 (PCO2) ("glacial,'' "present,'' and "year 2100'' atmospheric CO2 concentrations) were investigated during a mesocosm bloom dominated by the coccolithophorid Emiliania huxleyi. The day-to-day dynamics of net community production (NCP) and net community calcification (NCC) were assessed during the bloom development and decline by monitoring dissolved inorganic carbon (DIC) and total alkalinity ( TA), together with oxygen production and 14 C incorporation. When comparing year 2100 with glacial PCO2 conditions we observed: ( 1) no conspicuous change of net community productivity (NCPy); ( 2) a delay in the onset of calcification by 24 to 48 hours, reducing the duration of the calcifying phase in the course of the bloom; ( 3) a 40% decrease of NCC; and ( 4) enhanced loss of organic carbon from the water column. These results suggest a shift in the ratio of organic carbon to calcium carbonate production and vertical flux with rising atmospheric PCO2. [less ▲]

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See detailWhole-system metabolism and CO2 fluxes in a Mediterranean Bay dominated by seagrass beds (Palma Bay, NW Mediterranean)
Gazeau, Frédéric; Duarte, C. M.; Gattuso, Jean-Pierre et al

in Biogeosciences (2005), 2(1), 43-60

Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments) were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma ... [more ▼]

Planktonic and benthic incubations (bare and Posidonia oceanica vegetated sediments) were performed at monthly intervals from March 2001 to October 2002 in a seagrass vegetated area of the Bay of Palma (Mallorca, Spain). Results showed a contrast between the planktonic compartment, which was on average near metabolic balance (-4.6 +/- 5.9 mmol O-2 m(-2) d(-1)) and the benthic compartment, which was autotrophic (17.6 +/- 8.5 mmol O-2 m(-2) d(-1)). During two cruises in March and June 2002, planktonic and benthic incubations were performed at several stations in the bay to estimate the whole-system metabolism and to examine its relationship with partial pressure of CO2 (pCO(2)) and apparent oxygen utilisation (AOU) spatial patterns. Moreover, during the second cruise, when the residence time of water was long enough, net ecosystem production (NEP) estimates based on incubations were compared, over the Posidonia oceanica meadow, to rates derived from dissolved inorganic carbon (DIC) and oxygen (O-2) mass balance budgets. These budgets provided NEP estimates in fair agreement with those derived from direct metabolic estimates based on incubated samples over the Posidonia oceanica meadow. Whereas the seagrass community was autotrophic, the excess organic carbon production therein could only balance the planktonic heterotrophy in shallow waters relative to the maximum depth of the bay ( 55 m). This generated a horizontal gradient from autotrophic or balanced communities in the shallow seagrass-covered areas, to strongly heterotrophic communities in deeper areas of the bay. It seems therefore that, on an annual scale in the whole bay, the organic matter production by the Posidonia oceanica may not be sufficient to fully compensate the heterotrophy of the planktonic compartment, which may require external organic carbon inputs, most likely from land. [less ▲]

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See detailVariability of the gas transfer velocity of CO2 in a macrotidal estuary (The Scheldt)
Borges, Alberto ULg; Vanderborght, Jean-Pierre; Schiettecatte, Laure-Sophie et al

Poster (2005)

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See detailPlanktonic and whole system metabolism in a nutrient rich estuary (the Scheldt estuary)
Gazeau, Frédéric; Gattuso, Jean-Pierre; Middelburg, Jack J. et al

in Estuaries (2005), 28(6), 868-883

Planktonic gross primary production (GPP), community respiration (CR), and nitrification (NIT) were measured monthly in the Scheldt estuary by the oxygen incubation method in 2003. No significant ... [more ▼]

Planktonic gross primary production (GPP), community respiration (CR), and nitrification (NIT) were measured monthly in the Scheldt estuary by the oxygen incubation method in 2003. No significant evolution of planktonic GPP was observed since the 1990s with high rates in the freshwater area (salinity 0; 97 6 65 mmol C m22 d21) decreasing seaward (22–37 mmol C m22 d21). A significant decrease of NIT was observed with regard to previous investigations although this process still represents up to 20% of total organic matter production in the inner estuary. Planktonic CR was highest in the inner estuary and seemed to be mainly controlled by external organic matter inputs. Planktonic net community production was negative most of the time in the estuary with values ranging from 2300 to 165 mmol C m22 d21. Whole estuary net ecosystem production (NEP) was investigated on an annual scale using the results mentioned above and published benthic metabolic rates. A NEP of 239 6 8 mmol C m22 d21 was estimated, which confirms the strong heterotrophic status of this highly nutrified estuary. NEP rates were computed from June to December 2003 to compare with results derived from the Land-Ocean Interaction in the Coastal Zone budgeting procedure applied to dissolved inorganic phosphorus and carbon (DIP and DIC). DIP budgets failed to provide realistic estimates in the inner estuary where abiotic processes account for more than 50% of the nonconservative DIP flux. DIC budgets predicted a much lower NEP than in situ incubations (2109 6 31 versus 242 6 9 mmol C m22 d21) although, as each approach is associated with several critical assumptions, the source of this discrepancy remains unclear. [less ▲]

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See detailNet ecosystem metabolism in a micro-tidal estuary (Randers Fjord, Denmark): evaluation of methods
Gazeau, Frédéric; Borges, Alberto ULg; Barrón, Cristina et al

in Marine Ecology. Progress Series (2005), 301

The metabolic status, the difference between organic matter production and consumption of an estuary (Randers Fjord, Denmark) has been assessed based on 2 field cruises in April and August 2001 and a ... [more ▼]

The metabolic status, the difference between organic matter production and consumption of an estuary (Randers Fjord, Denmark) has been assessed based on 2 field cruises in April and August 2001 and a number of approaches: (1) the oxygen (02) incubation method, (2) dissolved inorganic carbon (DIC) budgets, (3) the response surface difference (RSD) method based on diel O-2 changes and (4) land-ocean interaction in the coastal zone (LOICZ) budgets based on dissolved inorganic phosphorus (DIP). Although each method has its own associated limitations and uncertainties, the above approaches converged most of the time in consistent metabolic estimates, both in sign and magnitude, and revealed that this system was near metabolic balance in spring (net ecosystem production: NEP similar to 0) and net heterotrophic in summer (NEP similar to -50 mmol C m(-2) d(-1)). In this shallow estuary (mean depth = 1.6 m), the benthic compartment was very active and represented 70 and 30% of the total gross primary production in April and August, respectively. NEP rates measured during this study are in the range of previously reported rates in estuaries. [less ▲]

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See detailDelayed and reduced coccolithophorid calcification under elevated PCO2
Delille, Bruno ULg; Harlay, Jérôme ULg; Zondervan, Ingrid et al

Poster (2004, May 10)

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and ... [more ▼]

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and give little information on the dynamics of calcification in natural conditions. The present work describes the development and decay of a nutrient-induced bloom of the coccolithophorid Emiliania huxleyi in a mesocosm experiment. The monitoring of Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TAlk) within the seawater enclosures allowed us to describe comprehensively day to day dynamics of both calcification and organic carbon production. Three atmospheric PCO2 conditions (glacial, present and next century) were simulated by bubbling CO2 mixtures, while total alkalinity was left to evolve from its present value. No conspicuous change of Net Community Production under elevated PCO2 was recorded while the production of inorganic carbon appeared to be affected in two ways. Firstly, the production rate of inorganic carbon appeared to be lowered by 40% in the next century PCO2 conditions, decreasing concomitantly the calcification to photosynthesis ratio from 0.75 (glacial conditions) to 0.45 (next century conditions). Secondly, the onset of calcification was delayed by 24~48h under elevated PCO2 conditions, reducing the overall length of calcification in the course of the bloom. These two effects would act to reduce the amount of precipitated CaCO3 by coccolithophorids in a High CO2 world [less ▲]

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See detailChromophoric dissolved organic matter in experimental mesocosms maintained under different pCO(2) levels
Rochelle-Newall, Emma; Delille, Bruno ULg; Frankignoulle, Michel et al

in Marine Ecology. Progress Series (2004), 272

Chromophoric dissolved organic matter (CDOM) represents the optically active fraction of the bulk dissolved organic matter (DOM) pool. Recent evidence pointed towards a microbial source of CDOM in the ... [more ▼]

Chromophoric dissolved organic matter (CDOM) represents the optically active fraction of the bulk dissolved organic matter (DOM) pool. Recent evidence pointed towards a microbial source of CDOM in the aquatic environment and led to the proposal that phytoplankton is not a direct source of CDOM, but that heterotrophic bacteria, through reprocessing of DOM of algal origin, are an important source of CDOM. In a recent experiment designed at looking at the effects of elevated pCO(2) on blooms of the coccolithophorid alga Emiliania huxleyi, we found that despite the 3 different pCO(2) levels tested (190, 414 and 714 ppm), no differences were observed in accumulation of CDOM over the 20 d of incubation. Unlike previous mesocosm experiments where. relationships between CDOM accumulation and bacterial abundance have been observed, none was observed here. These results provide some new insights into the apparent lack of effect of pCO(2) on CDOM accumulation in surface waters, and question the previously proposed mechanisms and rates of CDOM production in natural phytoplankton blooms. [less ▲]

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See detailGas transfer velocities of CO2 in three European estuaries (Randers Fjord, Scheldt and Thames)
Borges, Alberto ULg; Delille, Bruno ULg; Schiettecatte, Laure-Sophie et al

in Limnology & Oceanography (2004), 49(5), 1630-1641

We measured the flux of CO2 across the air–water interface using the floating chamber method in three European estuaries with contrasting physical characteristics (Randers Fjord, Scheldt, and Thames). We ... [more ▼]

We measured the flux of CO2 across the air–water interface using the floating chamber method in three European estuaries with contrasting physical characteristics (Randers Fjord, Scheldt, and Thames). We computed the gas transfer velocity of CO2 (k) from the CO2 flux and concomitant measurements of the air–water gradient of the partial pressure of CO2 (pCO2). There was a significant linear relationship between k and wind speed for each of the three estuaries. The differences of the y-intercept and the slope between the three sites are related to differences in the contribution of tidal currents to water turbulence at the interface and fetch limitation. The contribution to k from turbulence generated by tidal currents is negligible in microtidal estuaries such as Randers Fjord but is substantial, at low to moderate wind speeds, in macrotidal estuaries such as the Scheldt and the Thames. Our results clearly show that in estuaries a simple parameterization of k as a function of wind speed is site specific and strongly suggest that the y-intercept of the linear relationship is mostly influenced by the contribution of tidal currents, whereas the slope is influenced by fetch limitation. This implies that substantial errors in flux computations are incurred if generic relationships of the gas transfer velocity as a function of wind speed are employed in estuarine environments for the purpose of biogas air–water flux budgets and ecosystem metabolic studies. [less ▲]

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See detailVariability of the gas transfer velocity of CO2 in a macrotidal estuary (The Scheldt)
Borges, Alberto ULg; Vandenborght, Jean-Pierre; Schiettecatte, Laure-Sophie et al

in Estuaries (2004), 27(4), 593-603

We report a large set of 295 interfacial carbon dioxide (CO2) flux measurements obtained in the Scheldt estuary in November 2002 and April 2003, using the floating chamber method. From concomitant ... [more ▼]

We report a large set of 295 interfacial carbon dioxide (CO2) flux measurements obtained in the Scheldt estuary in November 2002 and April 2003, using the floating chamber method. From concomitant measurements of the air-water CO2 gradient, we computed the gas transfer velocity of CO2. The gas transfer velocity is well correlated to wind speed and a simple linear regression function gives the most consistent fit to the data. Based on water current measurements, we estimated the contribution of water current induced turbulence to the gas transfer velocity, using the conceptual relationship of O’Connor and Dobbins (1958). This allowed us to construct an empirical relationship to compute the gas transfer velocity of CO2 that accounts for the contribution of wind and water current. Based on this relationship, the spatial and temporal variability of the gas transfer velocity in the Scheldt estuary was investigated.Water currents contribute significantly to the gas transfer velocity, but the spatial and temporal variability (from daily to seasonal scales) is mainly related to wind speed variability. [less ▲]

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See detailBiogeochemistry of the Scheldt estuary and plume
Sirjacobs, Damien ULg; Shimoni, Michal; Borges, Alberto ULg et al

Conference (2003, September)

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See detailSCHELDT - Airborne Hyperspectral Potential for Coastal Biogeochemistry of the Scheldt Estuary and Plume
Shimoni, Michal; Sirjacobs, Damien ULg; Borges, Alberto ULg et al

Report (2003)

European estuaries are subject to intense anthropogenic disturbance reflected in elevated loading of detrital organic matter, which induce high respiration rates and the production of large quantities of ... [more ▼]

European estuaries are subject to intense anthropogenic disturbance reflected in elevated loading of detrital organic matter, which induce high respiration rates and the production of large quantities of dissolved CO2. The Scheldt basin covers one of the most populated and industrialised areas of Europe and its tributaries drain an area of about 21,860 km2. The amounts of nutrients discharged by the Scheldt increased considerably during the past 20 years. Due to the dilution and metabolic processes of the downstream river flow in the estuary, an important variability of several parameters can be observed amongst which phytoplankton species and concentration, particulate organic matter, colour dissolved organic matter and suspended matter. In the present days, researches on the functioning of estuarine and coastal ecosystems are based on highly time consuming, costly sea campaigns and laboratory analyses. Although optical spaceborne remote sensing already proved useful in such coastal ecosystem studies, hyperspectroscopy opened a new dimension by allowing improved distinction of various biogeochemical compounds through characteristic spectral signature identification. Water quality variables were examined in the Scheldt estuary and plume, using CASI-2 (Compact airborne Spectrographic Imager) hyperspectral sensor and in situ bio-optical observations. The numerous parameters and spectrum measured in each station were used for further remote sensing analysis, as well as to complete the interpretation of the observed environmental processes. Multiple regression approach has been used to derive correlation between classical ground truth measurements and the rich information provided by the numerous CASI spectral bands. From these relations, some synoptic maps of biogeochemical parameters could be derived in the Scheldt estuary and plume. [less ▲]

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See detailAtmospheric CO2 flux from mangrove surrounding waters
Borges, Alberto ULg; Djenidi, Salim ULg; Lacroix, Geneviève et al

in Geophysical Research Letters (2003), 30(11),

[1] The partial pressure of CO2 (pCO(2)) was measured at daily and weekly time scales in the waters surrounding mangrove forests in Papua New Guinea, the Bahamas and India. The pCO(2) values range from ... [more ▼]

[1] The partial pressure of CO2 (pCO(2)) was measured at daily and weekly time scales in the waters surrounding mangrove forests in Papua New Guinea, the Bahamas and India. The pCO(2) values range from 380 to 4800 muatm. These data, together with previously published data, suggest that overall oversaturation of CO2 with respect to atmospheric equilibrium in surface waters is a general feature of mangrove forests, though the entire ecosystems (sediment, water and vegetation) are probably sinks for atmospheric CO2. The computed CO2 fluxes converge to about +50 mmolC m(-2) day(-1). If this conservative value is extrapolated for worldwide mangrove ecosystems, the global emission of CO2 to the atmosphere is about 50 10(6) tC year(-1). Based on this tentative estimate, mangrove waters appear to be regionally a significant source of CO2 to the atmosphere and should be more thoroughly investigated, especially at seasonal time scale. [less ▲]

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See detailAirborne hyperspectral potential for coastal biogeochemistry of the Scheldt estuary and plume
Shimoni, Michal; Sirjacobs, Damien ULg; Borges, Alberto ULg et al

Conference (2003, June)

Estuaries are obligate pathways for the transfer of dissolved and particulate material from the continent to the marine system. The tidal regime of some estuaries leads to an increased residence time of ... [more ▼]

Estuaries are obligate pathways for the transfer of dissolved and particulate material from the continent to the marine system. The tidal regime of some estuaries leads to an increased residence time of the freshwater in the estuarine mixing zone and pronounced changes in the speciation of elements. European estuaries are subject to intense anthropogenic disturbance reflected in elevated loading of detrital organic matter, which induce high respiration rates and the production of large quantities of dissolved CO2. The Scheldt basin covers one of the most populated and industrialised areas of Europe and its tributaries drain an area of about 21,860 km2. The amounts of nutrients discharged by the Scheldt increased considerably during the past 20 years. Due to the dilution and metabolic processes of the downstream river flow in the estuary, an important variability of several parameters can be observed amongst which phytoplankton species and concentration, particulate organic matter, colour dissolved organic matter and suspended matter. In the present days, researches on the functioning of estuarine and coastal ecosystems are based on highly time consuming, costly sea campaigns and laboratory analyses. Although optical spaceborne remote sensing already proved useful in such coastal ecosystems studies, hyperspectroscopy opened a new dimension by allowing improved distinction of various biogeochemical compounds through characteristic spectral signature identification. The goal of this research is to explore the potential of CASI-SWIR airborne hyperspectroscopy in retrieving some of the biogeochemical parameters of interest in the Schedlt estuary and plume (Belgium-Netherlands coastal zone). A 13 sampling stations field survey was realised in order to cover as quickly as possible the wide range of water quality encountered from the mouth of the estuary to the outer limit of the plume. The numerous parameters and spectrum measured in each station were used for further remote sensing analysis, as well as to complete the interpretation of the observed environmental processes. Correlation was searched between classical ground truth measurements and the rich information provided by numerous CASI-SWIR spectral bands carefully chosen. These relations were used as an attempt to derive synoptic view of the spatial distribution of various biogeochemical parameters in the Scheldt estuary and plume. Synthesis of these hyperspectral-mapping products with other complementary satellite maps and ground data set may allow ocean scientists to derive substantial information about ecosystem processes in the Scheldt estuary and adjacent coast. [less ▲]

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See detailAirborne hyperspectral potential for coastal biogeochemistry of the Scheldt estuary and plume
Shimoni, Michal; Sirjacobs, Damien ULg; Borges, Alberto ULg et al

Conference (2003, May)

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See detailCalcification and organic production of coccolithophorids Emiliania huxleyi under different atmospheric pCO2 in a mesocosm experiment
Delille, Bruno ULg; Harlay, Jérôme ULg; Chou, Lei et al

Poster (2003, January 07)

The response of primary production and calcification of the coccolithophorid Emiliania huxleyi to different partial pressures of CO2 (p CO2) have been investigated during a mesocosm bloom experiment in a ... [more ▼]

The response of primary production and calcification of the coccolithophorid Emiliania huxleyi to different partial pressures of CO2 (p CO2) have been investigated during a mesocosm bloom experiment in a Norwegian fjord. Glacial, present and next century atmospheric p CO2 conditions (respectively 180, 370 and 700 ppmV) have been simulated above the surface of large sea-water enclosures. If production of organic matter remains constant under elevated p CO2, the production of inorganic carbon appears to be affected in two ways. First, the beginning of calcification is delayed. Second, the production rate of inorganic carbon appears to be lowered by 40% in the future conditions, decreasing subsequently the calcification/photosynthesis ratio from 1 to 0.6. During the experiment a strong viral growth have been experienced, which have seriously depressed calcification as well. We propose the threshold of 5.10 6 cell/ml for E huxleyi virus abundance above which the production and calcification of the population of E. huxleyi are severely affected. [less ▲]

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See detailDistribution of surface carbon dioxide and air-sea exchange in the English Channel and adjacent areas
Borges, Alberto ULg; Frankignoulle, Michel

in Journal of Geophysical Research (2003), 108(C5),

In the present paper we report the distribution of the partial pressure of CO2 (pCO2) in surface waters along 13 transects in the English Channel, covering the four seasons. The spatial and temporal ... [more ▼]

In the present paper we report the distribution of the partial pressure of CO2 (pCO2) in surface waters along 13 transects in the English Channel, covering the four seasons. The spatial and temporal variability of pCO2 is controlled by a complex combination of primary production (from May to June), degradation of organic matter, temperature change, and freshwater inputs. Preliminary air-sea CO2 exchange computations suggest that the Channel is not a major sink of atmospheric CO2 and is probably neutral from the point of view of atmospheric coupling. This is mainly related to a relatively low export and/or burial of organic carbon and intense benthic calcification. [less ▲]

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See detailFronts and mesoscale variability in the southern Indian Ocean as inferred from the TOPEX/POSEIDON and ERS-2 altimetry data
Kostianoy, Andrey G.; Ginzburg, Anna I.; Lebedev, Sergey Anatolievich et al

in Oceanology (2003), 43(5, SEP-OCT), 632-642

Charts of sea level anomalies (SLA) based on the combined altimetry data from the TOPEX/POSEIDON and ERS-2 satellites, as well as the corresponding charts of the sea surface dynamic heights (constructed ... [more ▼]

Charts of sea level anomalies (SLA) based on the combined altimetry data from the TOPEX/POSEIDON and ERS-2 satellites, as well as the corresponding charts of the sea surface dynamic heights (constructed by the superposition of SLA distributions over the climatic dynamic topography) and the temperature gradients at the ocean surface on the basis of the satellite Multi-Channel Sea Surface Temperature (MCSST) data, were used to study the mesoscale variability related to the fronts in the Southern Indian Ocean (30degrees-60degrees S, 20degrees-150degrees E). An analysis of these three types of satellite information for the central weeks of each month during the period from 1997 to 1999 allowed us to distinguish zones of enhanced meandering (eddy formation) within the basin under study, as well as the contributions of individual fronts and their interaction to the regional mesoscale variability. The problems of the correlation between the intensity of mesoscale variability and peculiarities of the local bottom topography and seasonal/interannual variability of mesoscale dynamics are addressed. [less ▲]

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See detailInorganic and organic carbon biogeochemistry in the Gautami Godavari estuary (Andhra Pradesh, India) during pre-monsoon : the local impact of extensive mangrove forests
Bouillon, Steven; Frankignoulle, Michel; Dehairs, Frank et al

in Global Biogeochemical Cycles (2003), 17(4),

[1] The distribution and sources of organic and inorganic carbon were studied in the Gautami Godavari estuary (Andhra Pradesh, India) and in a mangrove ecosystem in its delta during pre-monsoon. In the ... [more ▼]

[1] The distribution and sources of organic and inorganic carbon were studied in the Gautami Godavari estuary (Andhra Pradesh, India) and in a mangrove ecosystem in its delta during pre-monsoon. In the oligohaline and mesohaline section (salinity 0–15) of the estuary, internal production of total alkalinity (TAlk) and dissolved inorganic carbon (DIC) was recorded, and the d13CDIC profile suggests that carbonate dissolution may be an important process determining the DIC dynamics in this section of the Godavari. The partial pressure of CO2 (pCO2) was fairly low along the entire salinity gradient, (293–500 ppm), but much higher and more variable (1375–6437 ppm) in the network of tidal mangrove creeks in the delta. Here, variations in the concentration and d13C of the DIC pool were shown to result largely from the mineralization of organic matter. The present study clearly identifies the mangrove creeks as an active site of mineralization and CO2 efflux to the atmosphere, but shows that these changes in the aquatic biogeochemistry are a localized feature, rapidly fading in the adjacent Kakinada Bay. Our data indicate that mineralization of dissolved organic carbon (DOC) of mangrove origin, and its subsequent efflux as CO2 to the atmosphere may represent an important fate for mangrove carbon. Although further quantification of this process in a variety of systems is required, we suggest that some of the current ideas on the role of mangroves in the carbon budget of the coastal zone may need to be reconsidered. [less ▲]

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